JP2877751B2 - Cryogen pump - Google Patents

Abstract

A cryogenic pump is disclosed for pumping liquified gas from one container to another container or a point of use. The pump has a main housing (12) defining a cylinder in which a hollow piston (34) is reciprocable by means of a piston rod (42) and divides the interior of the main housing into a supercharger chamber (50) and a sump chamber (52). The lower end of the main housing is closed by a block (24) formed with a fixed piston (54), defining a high pressure chamber (60) in the hollow piston (34), and with inlet ports (76) leading into the sump chamber (52). An outer housing (14) defines a precharge chamber (82) around the main housing (12). During reciprocation of the hollow piston (34), liquid is drawn in through the ports (76) and progressively pumped, though non-return valves, in sequence through the sump chamber (52), the precharge chamber (82), the supercharger chamber (50), and the high pressure chamber (60) to an outlet line (136). The block (24) is located within and adjacent to the bottom of the container. The pump arrangement allows the container to be substantially emptied thereby avoiding waste of the contained liquified gas. <IMAGE>

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a mechanical pump, and more particularly to a cryogen pump for pumping a liquefied gas in a saturated liquid state.

[0002]

BACKGROUND OF THE INVENTION Refrigerant liquids or fluids, such as hydrogen, oxygen, nitrogen, argon, and liquefied hydrocarbons, ie, methane or natural gas, are stored and transported primarily in pressurized vessels. This container is particularly well-sealed and frozen to very low temperatures. Pumps are used to transport such cryogen fluid between containers or from one container to the point of use. While many pumps have been developed over the years, reciprocating mechanical pumps have been preferred for many applications. Such mechanical cryogen pumps have been required to have a net positive suction head (NPSH), i.e., a suction head higher than zero, to prevent pump clogging loss or to prevent cavitation. . Flow restrictions are generally the result of maintaining NPSH, and it is desirable to employ a pump that can operate with a negative suction head or NPSH below zero.

An example of such a mechanical cryogen pump is disclosed in US Pat. No. 5,188,519 issued to Spragis.
No. is illustrated. The pump disclosed in this patent has one cylinder having a fluid inlet and a fluid outlet, and one reciprocable cylinder in the cylinder between the fluid inlet and the fluid outlet.
And two pistons. The piston has a fluid passage extending therethrough and generally concentric with the cylinder, the fluid passage communicating with one inlet end communicating with a fluid inlet of the cylinder and a fluid outlet of the cylinder. One outlet end. One piston rod is attached to the piston so that the piston can reciprocate in the cylinder toward the cylinder fluid outlet. One valve operatively interlocked between the piston rod and the piston fluid passage inlet end alternately opens and closes the inlet at the passage, and the valve moves the piston rod and piston toward the cylinder passage outlet. Closes when moving and opens when the piston rod and piston are moved in opposite directions.

Another example of a reciprocating cryogen pump is disclosed in US Pat. No. 4,239,460 issued to Golz, which describes a pump designed to operate at less than zero NPSH. Have been. The pump employs a single reciprocating piston, which divides the cylindrical housing into a suction chamber and a discharge chamber. One gas inlet hole extends through the side of the housing and is configured to introduce liquefied gas into the suction chamber. One stationary piston extends from the outlet end of the housing into the discharge chamber. The fixed piston is slidably fitted in a cylindrical skirt held by the reciprocating piston to form a high-pressure chamber. The pressurized liquefied gas is supplied to the outlet through a passage in the fixed piston. A one-way valve controls the flow of liquefied gas through the inlet, the various chambers, and the outlet.

[0005] The applicant has the name cryogen pump, application no.
8/384970, filed February 7, 1995 (U.S. Pat. No. 5,511,955), discloses an improved mechanical pump in a pending application assigned to the assignee of the present application, wherein There is one reciprocating piston disposed in one first cylindrical housing, which divides the interior of the housing into one supercharging chamber and one discharging chamber opposite the piston. I have. At least one supercharging chamber inlet hole extends directly behind the reciprocating piston through the tubular housing to allow liquefied gas to be introduced from the liquefied gas inlet into the supercharging chamber. One fixed piston is mounted on the housing and extends into the discharge chamber. The fixed piston is fitted to a skirt held by the movable piston to form one high-pressure chamber between the movable piston and the fixed piston. A liquefied gas outlet extends from the high pressure chamber through the stationary piston to a final outlet. Excess fluid from the supercharging chamber is preferably discharged through one or more restrictive orifices into the storage container, obviating the need for a pressure reducing valve.

[0006]

These reciprocating mechanical pumps have one similar drawback, because they are not adapted to be immersed in a cryogen fluid container. The contents of such containers cannot be emptied, due to the arrangement of the various components, including the liquefied gas inlet. Some of the cryogen fluid remains in the container. It is an advance in the art to provide an improved cryogen pump that can be submerged in a cryogen container and draw all or most of the fluid from such a container.

[0007]

SUMMARY OF THE INVENTION An improved cryogen pump for submerging in a pressurized cryogen container for transferring liquefied gas within the container to another container or point of use. According to the invention, it comprises one reciprocating piston arranged in one inner cylindrical housing. The piston divides the interior of the inner housing into one charging chamber and one reservoir opposite the piston. At one end of the pump, one liquefied gas inlet extends between the liquefied gas container and the storage chamber, and the liquefied gas is introduced from the pressurized container into the pump. One outer housing surrounds the inner housing, forming a liquefied gas reservoir or preload chamber therebetween. A single supercharging chamber inlet hole extends through the cylindrical inner housing immediately after the reciprocating piston and is configured to introduce liquefied gas into the supercharging chamber from the precompression chamber gas inlet. A fixed piston is mounted within the housing and extends into the reservoir. The fixed piston is fitted on a skirt held by the movable piston, and forms a high-pressure chamber between the movable piston and the fixed piston. A liquefied gas outlet extends from the high pressure chamber through a fixed piston. The structure and operation of the present invention can best be understood by referring to the following description, taken in conjunction with the accompanying drawings, in which like parts are numbered the same.

[0008]

1, a liquefied gas pump 10 according to the present invention comprises an inner cylindrical housing 12 and an outer cylindrical housing 14 surrounding the inner cylindrical housing. ing. The inner cylindrical housing has one inner housing inlet end 16, one pump inlet / outlet end 18, one central portion 20, and one longitudinal axis 22. Inner housing entrance end 1
6 is formed integrally with the central part 20, while the pump inlet / outlet end comprises a single combined pump inlet / outlet head 24, which is the end of the inner tubular housing 12 and the outer tubular housing. 14 is shown as a disk-shaped block portion located inside the end. One O-ring 2
6 fits within the annular groove of the disc-shaped block portion to provide liquid tightness with the inner wall 28 of the outer tubular housing 14 (described in more detail below). One end plate 30 is fastened to the disc-shaped block portion by a plurality of bolts 31, thereby closing the end 32 of the outer cylindrical housing and the bottom end of the pump 10, and the pump 10 is liquefied. It sits near the bottom of the gas container (shown in more detail in FIG. 7).

[0009] The 1 mounted in the inner cylindrical housing 12
The reciprocating pistons 34 reciprocate along the longitudinal axis 22 in the housing. One drive rod 36 extends rearward from the reciprocating piston 34, and both are integrally formed as shown in FIG. The drive rod 36 extends through a rearward extension 38 of the inner cylindrical housing 12. A shaft seal 40 located between the drive rod 36 and the inner cylindrical wall of the rear extension 38 prevents leakage of liquid along the drive rod 36. The drive rod 36 is connected to a suitable drive mechanism, such as an electric motor and a cam arrangement (not shown), for example, via a hollow cam follower rod 42. The cam driven rod 42 includes a driving rod 36 and a reciprocating piston 34.
And back and forth to provide pumping action for this mechanical pump arrangement. Drive rod 36 and cam driven rod 4
The two can be connected by cooperating screw portions 44.

The reciprocating piston 34 has a forwardly projecting cylindrical skirt 46 which has an annular ring groove and a piston ring 48 which is formed by the inner cylindrical housing 1.
2 is engaged with the inner wall of the central portion 20. The reciprocating piston 34 connects the inside of the inner housing 12 with one supercharging chamber 50 at the inlet end 16 of the inner cylindrical housing 12 and the pump inlet / outlet.
The reservoir is partitioned into a reservoir 52 at the discharge end 18, and the reservoir is a low-pressure chamber.

A fixed piston 54 extends from the pump inlet / discharge head 24 into the reciprocating piston skirt 46. The fixed piston 54 includes a piston ring 56,
This piston ring is engaged with the cylindrical inner wall 58 of the skirt 46. A high-pressure chamber 60 is formed between the reciprocating piston 34 and the fixed piston 54. A single plug 62 threaded to the pump inlet / drain head 24 extends through the inlet / drain head into the stationary piston 54. The plug 62 is secured to the inlet / discharge head 24 by cooperating screws 64 between the plug 62 and the inlet / discharge head 24, and a gasket 66 seals the plug 62 to the inlet / discharge head. Outlets or outlet holes 68, 72, 7
O extends through the end of the fixed piston 54, plug 62, inlet / discharge head 24. More specifically, FIG.
And in the inlet / discharge head 24, the central hole 72 traverses through the plug 62,
The central hole 72 is concentric with a fixed piston end hole 74 in the end of the fixed piston 54.

Liquid from the container enters the pump 10 through a plurality of inlet holes 76, which extend from the end plate 30 and the pump inlet / discharge head 24 into the reservoir 52. One flat plate-shaped reservoir chamber valve 78 is movable along the axis from the closed position shown in FIG. 1 to the open position,
In the open position, the flat valve engages a retainer ring 80 fixed in the annular groove of the fixed piston 54. The reservoir 52 provides an initial chamber for fluid entering the pump 10 from a storage container. The fluid is sucked into the reservoir when the reservoir is in a low pressure state.

A preload chamber 82 or preload fluid reservoir is formed between the inner cylindrical housing 12 and the outer cylindrical housing 14. The two cylindrical housings are arranged concentrically and are closed at one end by an end cap 84 and at the other end by a discharge head 24. Annular O-ring 86
Seal the respective ends of the pump. The preload chamber 82 is connected to the reservoir chamber 52 by liquid, and at that time, the ball valve 88 moves to open the hole 90 between both chambers. The preload chamber 82 provides a second chamber area of the pump 10.

A third fluid chamber is provided in a supercharging chamber 50. Inner housing inlet end 16 of inner housing 12
Has a plurality of holes or passages 94 (shown in FIGS. 1 and 4) that connect fluid from the preload chamber 82 into the charging chamber 50. The supercharging chamber 50 is located immediately after the reciprocating piston 34. Another flat plate-shaped supercharging valve 96 moves along the longitudinal axis from the closed position shown in FIG. 1 to the open position, where the flat plate engages a retainer ring 98 fixed to the inner housing. I do.

A single high pressure chamber 60 forming a fourth chamber is in front of the supercharging chamber 50 and more particularly, as shown in FIGS. It is received at the appropriate time via the suction valve 102. The suction valve 102 includes a tapered plate head 104 and a stem 106, and the stem is slidably mounted in a bush 108. A bush 108 made of steel backed Molly Teflon material (commonly referred to as a DU bush) is pressed into the rear of the skirt 46 of the reciprocating piston 34. The valve body 110 of the suction valve 102 is provided with a hole 112 (see FIG. 5), which is provided with a passage 94 in the rear of the reciprocating piston 34 (see FIGS. 1 and 3).
At the same time, the liquefied gas is allowed to enter the high pressure chamber 60 from the supercharging chamber 50, at which time the suction valve 102 is open (ie, FIG. 1).
Has been moved to the right from the position shown in). The suction valve 102 is biased to a closed position by a spring 116 disposed between the bush and the lock nut 118 on the stem 106, as shown in FIG. Spring 11
The compression force of No. 6 can be adjusted by a lock nut 118, which is screwed into the threaded rear of the stem 106 (the adjustment range is a range where proper movement of the valve is obtained). .

The fluid in the high pressure chamber is discharged from the pump at the appropriate times of the pump cycle through the aforementioned outlet holes 68, 70, 72. One discharge valve 120 is disposed between the upstream end of the plug hole 72 and the fixed piston end hole 74;
This discharge valve is connected to the discharge valve seat 12 on the inner surface of the fixed piston 54.
8, the valve seat controls opening and closing of the fixed piston end hole 74. When the discharge valve 120 is pushed forward (to the discharge end), fluid flows through the fixed piston end hole 74 and through the peripheral space 130 between the fixed piston 54 around the valve 120 and the valve 120, and more specifically. As shown in FIG. 6, the evacuation duct or cross hole 132 enters the longitudinal hole 72. One outlet or discharge channel 136 is connected to the inlet / discharge head 24 and receives high pressure discharged liquefied gas as shown in FIGS.

If the pressure in the supercharging chamber 50 becomes too high,
The reciprocating piston 34 includes a poppet valve 138 that relieves pressure through a central hole in the drive rod 36 of the reciprocating piston to a concentric hole in the cam driven rod 42. Excess fluid or gas discharged through the drive rod 36 returns to the container again and is reused. Leakage occurs during the retraction stroke of the reciprocating piston 34, which will be described in more detail below.

In operation, during the retraction stroke of the reciprocating piston 34 (ie, movement away from the inlet / discharge head), the following operations occur. (1) The pressure in the storage chamber 52 decreases, and the high-pressure liquefied gas in the storage container acts on the disk valve 78 and is sucked into the storage chamber 52. (2) The liquefied gas and the vapor are compressed by reducing the volume in the supercharging chamber 50. This increased pressure liquefies the vaporized gas in the supercharging chamber, and this high pressure fluid
Of the inlet / discharge head 2 against the elasticity of the spring 116
Push in four directions, which allows liquefied gas to enter the high pressure chamber 60. (3) Due to the pressure increase in the supercharging chamber 50, the supercharging disc valve 96 moves toward the inlet end 16 of the inner housing 12 (to the left in FIG. 1) and closes.

During the return or forward movement of the reciprocating piston 34, that is, the stroke toward the discharge end, the following operation occurs. (1) While the reciprocating piston 34 is moving forward, the volume of the reservoir chamber 52 decreases and pushes the ball valve 88 against the inner wall of the outer chamber (see the position of the ball indicated by a broken line in FIG. 1). This action opens a hole 90 to allow a mixture of liquefied gas and vapor in the reservoir to enter the preload chamber 82. (2) The volume in the supercharging chamber 50 increases as a result of the forward movement of the reciprocating piston 34, and a low pressure is generated therein. This low pressure advances the supercharging valve 96 until it hits the retainer ring 98, and the valve opens. The liquefied gas flows into the supercharging chamber 50 until the reciprocating piston 34 reaches the end of the forward stroke. (3) The liquefied gas in the high pressure chamber 60 is controlled by the discharge valve 120 and the valve seat 1.
28, and towards the inlet / discharge head 24, which opens the valve. The pressurized liquefied gas enters the stationary piston through the end hole 74 and further through the center hole in the plug 62 and the discharge duct 70 in the inlet / discharge head 24 to the discharge passage 136. The pressure in the high pressure chamber keeps the suction valve 102 closed during the forward travel of the reciprocating piston 34.

As shown in FIG. 7, the inlet / outlet end of the pump 10 is located near the bottom 140 of the liquefied gas container 142. The pump inlet is located at the bottom 140 of the container.
, Substantially all of the liquefied gas in the container can be taken out more easily. Suitable opening 146 inside
A single bracket 144 with the pump supports the pump in the container. The pump design of the present invention is particularly useful in applications where the cryogen container or tank is installed in a vehicle because the pump operation is not affected by the turbulence of the fluid in the tank.

The foregoing detailed description of the preferred embodiments is an optimal embodiment contemplated by the inventors for carrying out the invention at the time of filing this application, and is provided by way of example and is provided by way of limitation. Not something. Accordingly, various modifications to the preferred embodiment described above are possible without departing from the scope of the invention. Thus, while the invention has been described and shown with respect to one particular embodiment, various changes and modifications which become obvious to those skilled in the art to which the invention pertains may be made within the spirit and scope of the claimed invention. It is possible.

[0022]

According to the pump structure of the present invention, the cryogen pump can be disposed in the liquefied gas container such that the liquefied gas inlet is disposed near the bottom of the container. Therefore, all or most of the liquefied gas in the container can be taken out in the moving or transporting step.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cryogen pump according to the present invention.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view taken along line 3-3 in FIG.

FIG. 4 is a sectional view taken along line 4-4 in FIG. 1;

FIG. 5 is an enlarged sectional view of a part of the pump taken along line 5-5 in FIG. 1;

FIG. 6 is an enlarged sectional view of a part of the pump taken along line 6-6 in FIG. 1;

FIG. 7 is a partial sectional view showing a state where the pump of FIG. 1 is immersed in a liquefied gas container.

[Explanation of symbols]

 12 inner cylindrical housing 14 outer cylindrical housing 18 pump inlet / outlet end 22 longitudinal axis 34 reciprocating piston 46 forward protruding cylindrical skirt 50 supercharging chamber 52 reservoir chamber 54 fixed piston 60 high pressure chamber 68, 72 outlet or discharge Hole 76 inlet suction port 78 reservoir chamber valve 88 ball valve 96 supercharging valve 102 suction valve 120 discharge valve 138 poppet valve

──────────────────────────────────────────────────の Continued on the front page (72) Robert E. Kroll, Inventor 13418, Carlos Fifth Court, Corpus Christi, Texas 78418, USA (72) Inventor Philip J. Westerman El, California 92630 Toro, Hazelwood No. 22952 (56) References JP-A-5-18351 (JP, A) U.S. Pat. No. 5,511,955 (US, A) UK Patent 264395 (GB, A) (58) Fields investigated (Int. ⁶ , DB name) F04B 25/00

Claims (16)

(57) [Claims] 1. An immersion type cryogen pump for transferring a liquefied gas from a container, having the following configuration: one main pump having one longitudinal axis and one discharge end. A single reciprocating piston arranged along the longitudinal axis in the main housing to partition the housing into a supercharging chamber and a storage chamber, wherein the capacity of the supercharging chamber and the storage chamber is Reversed by movement of the piston toward or away from the discharge end of the housing; one fixed piston extending into the reservoir, with a variable volume high pressure between the reciprocating piston and the fixed piston. Forming a chamber; a liquefied gas inlet extending through the housing and communicating with the sump near the discharge end; a single sump valve wherein the reciprocating piston moves away from the discharge end When moving in the direction One preload chamber; one preload chamber valve connecting the reservoir and the preload chamber, allowing liquefied gas to flow from the reservoir to the preload chamber. A single supercharging valve connecting the preload chamber and the supercharging chamber to allow liquefied gas to flow from the preload chamber to the supercharging chamber; Connecting the chamber to the supercharging chamber and allowing gas to flow from the supercharging chamber to the high pressure chamber; one high pressure outlet passage in fluid connection with the high pressure chamber; Pieces discharge valve. 2. The refrigeration pump according to claim 1, wherein the liquefied gas inlet is formed of a plurality of holes communicating with the reservoir chamber and being parallel to the longitudinal axis. 3. The refrigerant pump according to claim 1, further comprising one high pressure relief valve for discharging excess liquefied gas from the supercharging chamber. 4. The refrigeration pump according to claim 1, wherein the reciprocating piston has a long hole concentric with the longitudinal axis, and the fixed piston extends into the long hole in the reciprocating piston. 5. The cryogen pump according to claim 4, wherein the outlet passage extends through the fixed piston. 6. The cryogen pump according to claim 5, wherein each of the storage chamber, the precompression chamber, the high pressure chamber, and the discharge valve is a one-way valve. 7. The cryogen pump according to claim 6, wherein the preload chamber is formed by an outer housing surrounding the main pump housing, and the preload chamber is formed between the two housings. 8. An immersion type cryogen pump for transferring liquefied gas from a container, having the following configuration: one longitudinal axis, one inner wall, and one inlet end. An outer housing surrounding the inner housing; a reciprocator slidably disposed within the inner housing along the longitudinal axis. A piston, wherein the inner housing is
The movable piston is provided with one skirt slidably fitted to the inner wall of the housing, and the volume of the supercharging chamber and the storage chamber is The reciprocating piston is changed in reverse by moving toward or away from the discharge end; a fixed piston that extends in the reservoir and slidably fits on the inner wall of the reciprocating piston skirt. A high-pressure chamber is formed between the reciprocating piston and the fixed piston; a liquefied gas inlet; a pre-pressure chamber in the outer housing, and a fluid connected to an inlet end of the inner housing. Connected to each other; a one-way reservoir valve connecting the liquefied gas inlet at the pump discharge end to the reservoir to store liquefied gas as the reciprocating piston moves away from the discharge end. Allow entry into room; one of one A preload chamber valve connecting the reservoir to the preload chamber to permit fluid to enter the preload chamber as the reciprocating piston moves toward the discharge end; Connecting the precompression chamber to the supercharging chamber to allow liquefied gas to enter the supercharging chamber as the reciprocating piston moves toward the discharge end; one one-way high pressure chamber valve, wherein the movable piston is Connecting the charging chamber to the high pressure chamber as it moves away from the discharge end; one outlet for the pressurized liquefied gas;
And a one-way discharge valve connecting the high pressure chamber to the outlet when the reciprocating piston moves toward the discharge end. 9. The liquefied gas inlet has a plurality of holes opened to the reservoir and parallel to the longitudinal axis.
A cryogen pump according to claim 1. 10. The cryogen pump according to claim 8, wherein the discharge end includes a discharge head that closes a discharge end of the inner housing. 11. The cryogen pump according to claim 10, wherein the discharge head comprises a block-shaped member, and the plurality of holes extend through the block-shaped member. 12. The block-shaped member includes one outlet duct, and connects the high-pressure chamber to an outlet.
A cryogen pump according to claim 1. 13. The cryogen pump according to claim 12, further comprising one outlet passage connected to the outlet duct. 14. The cryogen pump according to claim 13, wherein the outlet duct opens into an outlet passage in a plane transverse to a longitudinal axis of the pump. 15. The refrigeration pump according to claim 8, further comprising one high-pressure relief valve so that excess liquefied gas can be discharged from the supercharging chamber. 16. The cryogen pump according to claim 10, wherein the fixed piston is formed integrally with a discharge head.